1. Field of the Invention
The present invention relates to a wet-type image forming apparatus provided in a copier, a printer, a facsimile or a multi-functional peripheral having these functions, as well as to a method of setting a transfer bias in such a wet-type image forming apparatus.
2. Description of the Related Art
Wet-type image forming apparatuses forming images using a liquid developer have been known, for example, from the disclosures of Japanese Laid-Open Patent Publication Nos. 08-328398 and 05-289544. The liquid developer used in such a wet-type image forming apparatus contains an insulating carrier liquid and granular toner (also referred to as toner particles) dispersed in the carrier liquid.
In the wet-type image forming apparatus, the liquid developer is drawn up from a developer tank and held on a surface of a developer carrier (developing roller). The toner in the liquid developer held on the developer carrier is transferred to an image carrier (photoreceptor), when a development bias is applied. An electrostatic latent image formed on the image carrier is visualized as a toner image, by the toner in the liquid developer.
The toner image on the image carrier is transferred to a transfer-receiving member such as a sheet of recording paper or an intermediate transfer body, when a transfer bias is applied. When the toner image is transferred to an intermediate transfer body, the toner image that has been transferred to the intermediate transfer body is transferred to a sheet of recording paper upon application of another transfer bias.
Toner particles used in the wet-type image forming apparatus using a liquid developer has particle diameter smaller than that used in a dry-type image forming apparatus. Because of the toner particles of smaller diameter, fine details of the image can be expressed on a sheet of recording paper. Thus, by the wet-type image forming apparatus using a liquid developer, images of high quality can be formed on a sheet of recording paper.